[PATCH 08/11] vfs: push EXDEV check down into ->remap_file_range
From: Dave Chinner <david@fromorbit.com>
Date: 2018-12-03 08:34:34
Also in:
linux-fsdevel, linux-nfs, linux-unionfs
Subsystem:
filesystems (vfs and infrastructure), the rest · Maintainers:
Alexander Viro, Christian Brauner, Linus Torvalds
From: Dave Chinner <redacted> before we can enable cross-device copies into copy_file_range(), we have to ensure that ->remap_file_range() implemenations will correctly reject attempts to do cross filesystem clones. Currently these checks are done above calls to ->remap_file_range(), but we need to drive them inwards so that we get EXDEV protection for all callers of ->remap_file_range(). Signed-off-by: Dave Chinner <redacted> --- fs/read_write.c | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-)
diff --git a/fs/read_write.c b/fs/read_write.c
index 3288db1d5f21..174cf92eea1d 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c@@ -1909,6 +1909,19 @@ int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in, bool same_inode = (inode_in == inode_out); int ret; + /* + * FICLONE/FICLONERANGE ioctls enforce that src and dest files are on + * the same mount. Practically, they only need to be on the same file + * system. We check this here rather than at the ioctl layers because + * this is effectively a limitation of the fielsystem implementations, + * not so much the API itself. Further, ->remap_file_range() can be + * called from syscalls that don't have cross device copy restrictions + * (such as copy_file_range()) and so we need to catch them before we + * do any damage. + */ + if (inode_in->i_sb != inode_out->i_sb) + return -EXDEV; + /* Don't touch certain kinds of inodes */ if (IS_IMMUTABLE(inode_out)) return -EPERM;
@@ -2013,14 +2026,6 @@ loff_t do_clone_file_range(struct file *file_in, loff_t pos_in, if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode)) return -EINVAL; - /* - * FICLONE/FICLONERANGE ioctls enforce that src and dest files are on - * the same mount. Practically, they only need to be on the same file - * system. - */ - if (inode_in->i_sb != inode_out->i_sb) - return -EXDEV; - if (!(file_in->f_mode & FMODE_READ) || !(file_out->f_mode & FMODE_WRITE) || (file_out->f_flags & O_APPEND))
--
2.19.1